1. Field of the Invention
The invention relates to an evaporator, a system for a motor vehicle for heating and/or cooling a battery, and a motor vehicle air conditioning system.
2. Description of the Background Art
Batteries of hybrid or electric vehicles must be heated or cooled in order to achieve an adequate operating temperature for the battery, for example in a temperature range between 0° C. and 40° C. When electrical energy is drawn from the battery or the battery is charged, the battery gives off heat; in consequence, the battery must be cooled so that it does not heat to temperatures of above 30° C. or 40° C. At low outdoor temperatures, for example below 0° C., heating of the battery is necessary so that electrical energy can be drawn from the battery and also so that charging with electrical energy is possible. To this end, the hybrid or electric vehicle has a coolant circuit with which the battery can be cooled and heated.
DE 101 28 164 A1, which corresponds to U.S. Pat. No. 6,705,101, which is incorporated herein by reference, and which discloses a vehicle cooling system for an electric or hybrid vehicle. The vehicle cooling system has a coolant circuit that is thermally coupled to a battery. Also built into the coolant circuit with the battery is an evaporator of a refrigeration circuit with a condenser, a compressor, and an expansion valve. The coolant circuit with the battery can be cooled by means of the evaporator, with the result that the battery can also be cooled by means of the refrigeration circuit. In addition, it is known to couple the coolant circuit for the battery with an ambient air heat exchanger in such a vehicle cooling system so that the battery can be cooled by emission of the heat to the ambient air without the refrigeration circuit being operated when outdoor temperatures are low.
From DE 10 2008 017 113 A1 is known an evaporator as heat exchanger for a motor vehicle. A plurality of plates are stacked parallel to one another as a heat exchanger in a plate-type or sandwich construction. A first flow chamber for refrigerant as the first fluid and a second flow chamber for a second fluid are formed between the plates so that heat can be transmitted from the second fluid to the refrigerant.
DE 195 23 475 C1 discloses a plate-type heat exchanger, in particular an oil cooler, having a stack of heat exchanger plates that are interleaved and connected to one another by joining techniques to form separate flow passages for the heat-exchanging media, and in which the inlet and outlet ports for at least one medium are located on the same side of the plate stack, having inserts provided in the inlet and outlet passages for flow redirection in a serpentine pattern, wherein one insert essentially blocks one inlet and outlet passage and the other insert lines portions of the other inlet or outlet passage in the manner of a sleeve, wherein the inserts are produced as a single injection molded part connected by a connecting part, and in that the inserts are removably attached in the inlet passage and in the outlet passage.
EP 2 107 328 A1, which corresponds to US 20090249810, which is herein incorporated by reference, discloses an evaporator, in particular for a motor vehicle, comprising a plurality of plates stacked parallel to one another in a vertical direction with apertures that are aligned with one another for supply and return of a first fluid implemented as refrigerant and of a second fluid, wherein formed between two adjacent plates are a flow passage of a first type for carrying the first fluid in alternation with a flow passage of a second type for carrying the second fluid, wherein a heat-transferring area of the plates has a length in the direction of refrigerant flow and a width perpendicular thereto, wherein the ratio of the length to the width is no greater than approximately 1.3.
Heat exchangers or chillers in plate-type constructions are used in systems to cool the batteries of hybrid or electric vehicles using a refrigeration circuit. In these systems, the heat exchanger or chiller has a plate-type construction and comprises a plurality of stack plates stacked atop one another such that a first fluid passage for the refrigerant and a second fluid passage for the coolant, for example water with an antifreeze, are formed between the stack plates. The refrigerant here is routed through the first fluid passage between the stack plates through at least two, preferably at least three, sections of the first fluid passage between the stack plates in opposite directions, which is to say in a serpentine pattern. In deviation from this, the refrigerant can also be routed in just one direction through the heat exchanger. It is necessary here to be able to shut off the heat exchanger as evaporator in the refrigeration circuit. For this reason, a shutoff unit is necessary, which requires additional installation space outside of the heat exchanger on the refrigerant lines. The shutoff unit is necessary because two heat exchangers or evaporators are arranged in the refrigeration circuit of the system, and they must be turned on and off individually.